Disperse bisanil dyes derived from diaminomaleonitrile and their preparation

ABSTRACT

Extremely bright, tinctorially strong disperse dyes derived from diaminomaleonitrile and selected aromatic and heterocyclic aldehydes, and their preparation, useful for dyeing and printing polyester and polyester-cotton blend fibers in yellow to blue shades of generally good fastness properties, which dyes are of the general formula

United States Patent [191 Neumer Dec. 16, 1975 [75] Inventor: John Fred Neumer, Hockessin, Del.

[73] Assignee: E. I. Du Pont de Nemours & Co.,

Wilmington, Del.

22 Filed: Jan.3, 1974 21 Appl. No.: 430,416

[52] US. Cl. 260/465 E; 260/240 G [51] Int. Cl. ..C07C 119/00; C07D'333/04;

[58] Field of Search 260/240 G, 465 E [56] References Cited UNITED STATES PATENTS 2,500,111 3/1950 Anish et al 260/240 G 2,766,243 10/1956 Middleton 2,849,449 8/1958 Cope et al. 260/240 G 3,179,692 4/1965 Martin 260/465 E UX 3,221,041 11/1965 Roland 260/465 E 3,657,213 4/1972 Ramanathan 260/465 E X 3,717,625 2/1973 Peter et al 260/465 E X 3,778,446 12/1973 Weigert 260/465 E X Primary ExaminerAllen B. Curtis [57] ABSTRACT Extremely bright, tinctorially strong disperse dyes derived from diaminomaleonitrile and selected aromatic and heterocyclic aldehydes, and their preparation, useful for dyeing and printing polyester and polyestercotion blend fibers in yellow to blue shades of generally good fastness properties, which dyes are of the general formula Ar,CH=N--C(CN)=C(CN)l l=Cl-lAr wherein Ar, and Ar are aromatic or aromatic-like groups, for example, phenyl or pyridyl.

36 Claims, N0 Drawings DISPERSE BISANIL DYES DERIVED FROM DIAMINOMALEONITRILE AND THEIR PREPARATION BACKGROUND OF THE INVENTION 1-. Field of the Invention This invention relates to yellow to blue bisanil disperse dyes prepared from diaminomaleonitrile.

2. Description of the Prior Art Monocondensation products of diaminomaleonitrile with various aldehydes are known in the art. Onoda in Nippon Nogeikagaku Kaishi, 36 (2), 167-72 (1962) discloses yellow monocondensation products diaminomaleonitrile with aldehydes; the products are of the formula wherein Ar is either phenyl, p-dimethylaminophenyl or furfuryl. Robertson and Vaughan in J. Am. Chem. Soc., 80, 2691 (195 8') disclose yellow monocondensation products of such formula wherein Ar is either phydroxyphenyl, p-nitrophenyl or cinnamyl. Reported attempts to introduce a second mole of the same aldehyde appear to have been unsuccessful and attempts to introduce a second mole of a different aldehyde with the monoanil (Schiff base) resulted in displacement of the aldehyde residue of the original derivative. Such displacement facilely occurred when the second aldehyde possessed a carbonyl carbon atom of greater electron deficiency than the original aldehyde; for example, p-nitrobenzaldehyde benzaldehyde p-hydroxyben-' zaldehyde (decreasing order of facility of displacement). I-Iinkel et al. in J. Chem. Soc., 1432 (1937) disclose yellow monocondensation products of such formula wherein Ar is either phenyl, p-anisyl, salicyl or mbromosalicyl. None of the aforementioned references discloses that the monoadducts of diaminomaleonitrile and aldehydes are useful as dyestuffs for synthetic fibers, especially polyester fibers.

US. Pat. No. 2,200,689 discloses heterocyclic pyrazinocyanine pigment dyestuffs which are obtainable by condensing diaminomaleonitrile with 1,2-dicarbonyl compounds, such as diacetyl, glyoxal, benzil, ortho-benzoquinone, acenaphthenequinones, thionaphthenequinones, phenanthrenequinones and aceanthrenequinones, at about 100-300C. in the presence of a solvent, pyridine and a metal salt. They are described as having good fastness properties.

Linstead et al. in J. Chem. 500., 91 1 (1937) describe a variety of phthalocyanine-type pigments which vary in color from blue to green with increasing molecular weight; they are prepared by treatment of 2,3 dicyanopyrazines of the formula R CN wherein R is H, CH or phenyl with copper salts. The

2,3-dicyanopyrazines can be prepared by condensation of diaminomaleonitrile with, respectively, glyoxal, di acetyl and benzil.

OBJECTS AND SUMMARY OF THE INVENTION The dye trade is continuously seeking new and better dyes for use in existing and newly developed dyeing and printing systems and for use with fibers, blended fibers and fabrics, which fabrics may, for example, be subjected to an after-treatment (after-dyeing) step, such as the application of a permanent press resin composition, to impart a particularly desirable property to the dyed fabric. Dyes which combine brightness of shade and high tinctorial strength with good application and fastness properties are particularly useful in such systems. Bright dyes are more attractive than dull dyes and offer greater versatility in formulating mixed shades. Commercial disperse dyes for use on polyester and other synthetic and semi-synthetic fibers tend as a class to have rather dull shades. Bright disperse dyes often suffer form poor lightfastness or high cost, or both.

It is an object of this invention to provide yellow to blue disperse dyes. It is a further object to provide dyes which exhibit outstanding brightness of shade and high tinctorial strength and which are generally fluorescent and significantly brighter than known existing disperse dyes. It is a still further object to provide disperse dyes with acceptable fastness to light and sublimation on polyester and polyester-cellulosic blend fibers. Yet another object is to provide economically attractive dyes derived from inexpensive starting materials. A further object is to provide a variety of processes for preparing such dyes.

In summary, this invention relates to bisanil disperse dyes (and their preparation) of the formula Ar,CI-l- =NC(CN)=C(CN)-N=CHAr wherein each of Ar and Ar is independently selected from 1. benzo(5- and 6-membered)heterocyclic groups containing 0-4 methyl substituents and 2. phenyl, naphthyl, S-membered heterocyclic and 6-membered heterocyclic groups containing 0-3 substituents selected from N0 halogen, CN, C aIkyl, C alkoxy, OCl-l -phenyl, phenyl, CF OH, OC alkylene-N(C alkyl) C alkylene-Cl, NI-ICONH NI-ICOA, NI-ISO A, SR SO R NHR,, NHCOC ,alkylene-B and NR R wherein:

a. R is C alkyl or C alkylene-k b. R is C alkyl, C alkylene R or, if Ar, or Ar is phenyl, C alkylene attached to a phenyl position which is ortho to the position to which the nitrogen is attached;

c. R, is CN, halogen, OI-I, phenyl, C alkoxy, 0C alkylene-Cl I, CO A, OCOA, OCONI-IA or CO C ,alkylene-OCOA;

(1. R is CN, halogen, OH, phenyl, OC alkylene-CN, CO A, OCOA, CO C ,alkylene-OCOA, A,

phthalimido, succinimido, glutarimido, OCOCI-l=C1-1 CH CH(OCOA)CH OA or CH C l-I( OCONHA )CH OA;

e. A is C alkyl or R f. B is halogen, C alkoxy or R g. R is phenyl containing 0-2 substituents selected from C alkyl, C alkoxy, halogen, N0 CN, C alkylCONH and NR R wherein each of R and R is independently selected from H and C alkyl, with at least one of R and R being C alkyl; and

DETAILED DESCRIPTION OF THE INVENTION The bisanil dyes of the above formula can exist in two isomeric forms, the cis arrangement NC CN N=CHAr C=C Furthermore.

the dyes can be symmetrical (if Ar and Ar are identical) or unsymmetrical (if Ar and Ar are different). The dyes can be prepared by condensing diaminomaleonitrile with the aldehydes Ar Cl-lO and Ar Cl-lO as hereinafter described, Ar Cl-lO and Ar CHO being the same or different. The present invention also relates to additional processes for preparing the heretofore defined symmetrical and unsymmetrical, cis-and trans-bisanil dyes.

Diaminomaleonitrile is generally referred to as HCN tetramer since it is available in low yields from the base catalyzed tetramerization of HCN as shown in U.S. Pat. No. 2,499,441. Tetramerization of HCN to diaminomaleonitrile also occurs in the presence of a catalytic amount of a basic catalyst and at least one of the cocatalysts diiminosuccinonitrile or cyanogen as shown in U.S. Pat. No. 3,629,318. Tetramerization of HCN in an aprotic solvent, such as dimethylsulfoxide, in the presence of a catalyst, such as sodium cyanide, at 60-70C. at atmospheric pressure, as shown in U.S. Pat. No. 3,704,797, provides yet another route to diaminomaleonitrile; such a procedure also is described in Chemical Week, July 12, 1972, page 36 and in European Chemical News, Mar. 2, 1973, page 20. Diaminomaleonitrile also can be prepared from diiminosuccinonitrile which itself is preparable, according to J. Org. Chem., 37, 4133 (1972), in high yield by the base catalyzed addition of HCN to cyanogen. Diiminosuccinonitrile can be converted by chemical reagents to diaminomaleonitrile, for example, by reaction thereof with HCN as shown in U.S. Pat. No. 3,564,039. Diaminomaleonitrile also can be prepared by reaction of diiminosuccinonitrile with hydrogen in the presence of a Group VIII transition metal hydrogenation catalyst as shown in U.S. Pat. No. 3,551,473.

The yellow to blue unsymmetrical bisanil disperse dyes can be prepared by condensing 1 mole of diaminomaleonitrile with 1 mole each of different aryl aldehydes Ar CHO and Ar CHO. Symmetrical bisanil dyes can be prepared by condensing 1 mole of diaminomaleonitrile with 2 moles of a single aryl aldehyde.

Examples of aryl aldehydes, Ar CHO and/or Ar CHO, which are useful in the preparation of the bisanil dyes are given in Table I.

TABLE I 4-[N,N-bis(methyl )amino]benzaldehyde 4-bromo-2 ,5-diisopropylbenzaldehyde 4- N,N-bis( n-propyl )am ino] -2-methylbenzaldehyde 6-formyl-N-(methyl )-2,2 ,4,7-tetramethyl-l ,2,3 ,4-tetrahydroquinoline -bromothiophene-2-carboxaldehyde 4'-[N-ethyl-N-( Z-methoxycarbonylethyl)amino1-2- methylbenzaldehyde 4- N-( 2-butoxycarbonylethyl )-N-ethylamino] -2 methylbenzaldehyde 4-ethylcarbonylamidobenzaldehyde N-methylindole-3-carboxaldehyde 4-thiomethoxybenzaldehyde 4-thio-n-butoxybenzaldehyde 4-thiomethoxynaphthaldehyde 4-phenylsulfonylbenzaldehyde 4-methylsulfonylbenzaldehyde 4'thio-( 2 '-hydroxyethoxy )benzaldehyde hyde 4-(N-cyanoethyl-N-methylamino)benzaldehyde 4-chlorobenzaldehyde 2,6-dichlorobenzaldehyde 2-nitrobenzaldehyde 3-nitrobenzaldehyde 4-nitrobenzaldehyde 4-[N,N-bis( ethyl)amino]benzaldehyde 4-[N,N-bis(ethyl)amino]-2-hydroxybenzaldehyde 3-hydroxybenzaldehyde Z-hydroxybenzaldehyde 4-hydroxybenzaldehyde 4-[N-cyanoethyl-N-ethylamino]-2-methylbenzaldehyde 4-[N,N -bis(hydroxyethyl)amino]benzaldehyde 4- N ,N-bis( cyanoethyl )amino ]benzaldehyde 4-[N,N -bis(n-propyl)amino]benzaldehyde 3-chloro-4-hydroxy-5-methoxybenzaldehyde 4-chloro-3-nitr0benzaldehyde 5-chloro-2-nitrobenzaldehyde 3,4-dibenzyloxybenzaldehyde 3,5-dibromosalicylaldehyde 3 ,S-di-tert.-butyl-4-hydroxybenzaldehyde 4-[2-(diethy1amino)-ethoxy]benzaldehyde 2,S-dihydroxybenzaldehyde 3,4-dihydroxybenzaldehyde 2,3-dimethyl-4-methoxybenzaldehyde 2,5-dimethyl-4-methoxybenzaldehyde 2,4-dimethylbenzaldehyde 2,5-dimethylbenzaldehyde 2-ethoxybenzaldehyde 4-ethoxybenzaldehyde 3-ethoxy-4-hydroxybenzaldehyde 4-cyanobenzaldehyde 4-acetamidobenzaldehyde 2-methoxybenzaldehyde 3-methoxybenzaldehyde 3-benzyloxybenzaldehyde 4-benzyloxybenzaldehyde 4-biphenylcarboxaldehyde 5-bromo-2-methoxybenzaldehyde 2-bromobenzaldehyde 3-bromolbenzaldehyde 5-bromosalicylaldehyde 5-bromovanillin[5bromo-4-hydroxy-3-methoxybenzaldehyde] 5-bromo-3 ,4-dimethoxybenzaldehyde 6-bromo-3,4-dimethoxybenzaldehyde 2-( 2-chloroethyl)benzaldehyde 2-chloro-6fluorobenzaldehyde 4-ethoxy -3-methoxybenzaldehyde 3-ethoxysalicylaldehyde 3-fluoro-4-methoxybenzaldehyde 3-fluorobenzaldehyde 4-fiuorobenzaldehyde 3-hydroxy-4-methoxybenzaldehyde 2-hydroxy-4-methoxybenzaldehyde 2-hydroxy-5-methyoxybenzaldehyde 4-hydroxy-3-methoxybenzaldehyde (vanillin) 2-hydroxy- 1 -naphthaldehyde benzalde- I 2 -acetamido-4'-[ N-( Z-methoxycarbonylethyl- )amino '-methoxybenzaldehyde 4' N ,N-bis( ethyl )amino ]-5 '-methoxy-2 3-methylbenzamido )benzaldehyde 2 '-chloroacetamido-4 N,N-bis( ethyl )amino ]-5 methoxybenzaldehyde 2 3-chlorobutyramido )-4 N,N-bis( cyanoethyl- )amino -5 '-methoxybe nzaldehyde 2 '-acetamido-4 N ,N-bis( 2-acetoxyethoxycarbonylethyl )amino -5 '-methoxybenzaldehyde 4'-[ N ,N-bis( 2-acetoxyethyl )amino ]-2 2- chlorobenzamido )-5 '-methoxybenzaldehyde 2 '-acetamido-4 [N- 2-acetoxyethyl )-N-cyanoethylamino ]-5 '-methoxybenzaldehyde 4'-[N-cyanoethyl-N-ethylamino1-5 -methoxy-2 4- nitrobenzamido )benzaldehyde 4 N-( Lmethoxycarbonylethyl )-N-methylamino benzaldehyde 4- N ,N-bis( 2-acetoxyethyl )amino1-2 -methylsulfonamidobenzaldehyde 4'- N-( Z-acetoxyethyl )-N'-cyanoethylamino]-2 phenylsulfonamidobenzaldehyde 4'-[N,N-bis( 2-acetoxyethyl)amino]-5 '-methoxy-2'- methylsulfonamidobenzaldehyde 4'-[ N-ethyl N-( 2-succinimidoethyl )amino]-2 methylbenzaldehyde 4 N-ethyl-N-( 2-phthalimidoethyl )amino ]-2 methylbenzaldehyde 4 N-cyanoethyl-N-( 2-succinimidoethyl )amino]-2 methylbenzaldehyde 4 N-ethyl-N-( Z-glutarimidoethyl )amino]-2 methylbenzaldehyde 6-formyl-N-( B-phenylcarbamoyloxyethyl )-2,2,4,7-

tetrar'nethyll ,2,3 ,4-tetrahydroquinoline 6-formyl-N-cyanoethyl-2,2,4,7-tetramethyl-1,2,3 ,4-

tetrahydroquinoline 6-formyl-N-( B-acetoxyethyl )-2,2,4,7-tetramethyll ,2,3,4-tetrahydroquinoline 6-formyl-N-( B-benzoyloxyethyl )-2,2,4 ,7-tetramethyll ,2,3 ,4-tetrahydroquinoline 4 N ,N-bis( Z-cyanoethylethoxyethyl )amino ]-2 methylbenzaldehyde 2 -acetamido-4 N-( 2-cyanoethyletho xyethyl )-N- ethylamino] benzaldehyde 4 N-ethyl-N-( Z-methylsulfonylethyl )amino -2 methylbenzaldehyde 4 N-cyanoethyl-N-( 2-phenylsulfonylethyl )amino benzaldehyde 4'-[ N-cyanoethyl-N-( 2-methoxyethylamino1benzaldehyde 8 4-[N-ethyl-N-( 2-propionoxyethyl )amino]-2 methylbenzaldehyde indole-2-carboxaldehyde N-ethylindole-3-carboxaldehyde N-(Z-acetoxyethyl)indole-3-carboxaldehyde thianaphthene-2-carboxaldehyde thianaphthene-3-carboxaldehyde 4,5-dibromothiophehe-2-carboxaldehyde 4-bromothiophene-2-carboxaldehyde thiophene-3-carboxaldehyde 5-[N,N-bis(ethyl)amino]indole-3-carboxaldehyde 5-[ N,N -bis( ethyl )amino thiophene-2-carboxaldehyde 5-[N,N-bis(methyl)amino] l ,3,4-thiadiazole-2-carboxaldehyde 5-[N,N-bis(ethyl )amino]- 1 ,4-thiazole-2-carboxaldehyde 4-bromofuran-2-carboxaldehyde pyridine-N-oxide-3-carboxaldehyde The aldehydes listed above are either commercially available or can be prepared by well known prior art procedures, such as the Vilsmeier reaction using dimethylformamide, phosphorous oxychloride and the appropriate substituted aryl compound.

Further to the above, the aryl aldehydes can be modified by the incorporation of sulfonic acid groups (SO H) to provide, when condensed with diaminomaleonitrile as described herein, acid dyes for potential use on nylon. Similarly, incorporation of basic groups (-N(alkyl) )can provide cationic dyes having potential utility on polyacrylonitrile and acid-modified polyester and polyamide fibers.

The symmetrical dyes, that is, bisanil dyes of the above formula wherein Ar and Ar are the same, can be prepared in one step by condensing 1 mole of diaminomaleonitrile with 2 moles of an aryl aldehyde, in the presence of an acidic catalyst, in an organic solvent, at -150C., while continuously removing the water formed during the reaction either by azeotropic distillation or bythe action of a dehydrating agent, such as phosphorus pentoxide or dicyclohexylcarbodiimide.

Preferred catalysts in the condensation include sulfuric acid, polyphosphoric acid and p-toluenesulfonic acid. Organic solvents, such as acetonitrile, tetrahydrofuran, dimethylformamide, hexamethylphosphoramide, dimethylacetamide, toluene, xylene, benzene and monochlorobenzene are equally useful. After cooling the reaction mixture to room temperature, the precipitated bisanil dyestuff can be isolated by filtration.

It has been discovered that condensation of 2 -moles of 4-[N,N-bis(ethyl)amino]benzaldehyde and 1 mole of diaminomaleonitrile at 50-55C. in hexamethylphosphoramide containing sulfuric acid as catalyst, in the presence of phosphorus pentoxide to remove the water of reaction, over a 6 hour period, provides the bright, fluorescent, red cis-bisanil dye N,N'- {4-N,N- bis( ethyl amino]benzylidene }diamin0 maleonitrile having the structure I The cis geometry about the central carbon-carbon double bond is evidenced by the large observed dipole moyielding mixtures of the cisand trans-symmetrical.

bisanils and the yellow monoanil species.

A useful one-step process for the preparation of symmetrical bisanil dyes involves the condensation of at least about 2 moles of aryl aldehyde with 1 mole of diaminolmaleonitrile in glacial acetic acid, at about the boiling temperature of the acid, for extended periods of time. This process provides the thermodynamically more stable trans isomer having the structure The low dipole moment of 3.2D on this product supports the structure assignment. Reaction times of up to about fourhours at l120C. generally are adequate for obtaining substantially trans isomer. Upon cooling to room temperature, the trans-bisanil crystallizes and can be isolated from the acid medium. Yields of 6075% of high purity symmetrical trans-bisanils can be obtained by this procedure. A similar result can be obtained by condensing 1 mole of the monoanil of diaminomaleonitrile with 1 mole of an aryl aldehyde under similar conditions to those described above.

The unsymmetrical bisanil byes, that is, bisanil dyes prepared from diaminomaleonitrile and two different aldehydes, can be prepared in stepwise fashion by monocondensation of 1 mole of a first aryl aldehyde with 1 mole of diaminomaleonitrile to provide the yellow monoanil derivative. The monocondensation is preferably run in an organic solvent, such as tetrahydrofuran, acetonitrile or benzene, for up to about four hours, at the boiling point of the solvent, in the presence of an acidic catalyst, such as sulfuric acid. The resultant yellow monoanil 1 mole) is then treated with 2 moles of a different aryl aldehyde in an organic solvent inthe presence of a secondary or tertiary amine catalyst, while azeotropically removing the water formed in the condensation. Preferred amine catalysts are piperidine and triethylenediamine. No condensation occurs in the absence of catalyst. Useful organic solvents include monochlorobenzene, acetonitrile, dimethylformamide, isopropanol, dichloroethane, toluene and benzene, the latter being most useful. By way of example of the stepwise condensation, diaminomaleonitrile (1 mole) is condensed with 4-[N,N-bis(ethyl)amino]benzaldehyde (1 mole) in tetrahydrofuran, in the presence of sulfuric acid, at 65C., for 3 hours; a high yield, for example, 80-90%, of the yellow monoanil N-{4- [N,N-bis( ethyl )amino benzylidine }diaminomaleonitrile is obtained. This intermediate monoanil possesses inherent deficiencies in application properties on polyester when compared to the bisanil. The monoanils, in general, also do not exhibit the fluorescence and brightness which are characteristic of the bisanil derivatives of diaminomaleonitrile. Subsequent condensation of the aforesaid monoanil (1 mole) with 2 moles of 4-chlorobenzaldehyde in benzene, in the presence of a catalytic amount of piperidine, at 7580C., while continuously azeotroping water over a six-hour period, provides, after removal of solvent, a 40-50% yield of the trans-unsymmetrical bisanil N-{4-[N,N-bis(ethyl)- amino]benzylidene}-N -(4-chlorobenzylidene)- diaminomaleonitrile having the structure CN N=CH Cl When the amount of basic catalyst is less than 0.50 mole per mole of monoanil, the trans-unsymmetrical is contaminated with the cisunsymmetrical dye and both the cis and trans forms of the symmetrical adduct N,N- {4 [N ,N-bis(ethyl)aminol-benzylidene} diaminomaleonitrile. The latter derivative is believed to be formed by initial hydrolysis of N-{-[N,Nbis(ethyl)amino] benzylidene}-N(4-chlorobenzylidene)diarnino maleonitrile to N-(4-chlorobenzylidene)diaminomaleonitrile and 4-diethylaminobenzaldehyde, followed by subsequent reaction of the latter aldehyde with the starting monoanil N-{4-[N.N-bis-(ethyl) amino]benzylidene}diaminomaleonitrile. The ratio of cis and trans products obtained does not change with longer reaction times, for example, up to about 18 hours. However, when the condensation is carried out with an increased amount of basic catalyst,

for example, 0.50 mole of catalyst to one mole of ucts capable of being formed by this process, the transunsymmetrical dyes are generally obtained only in moderate yields and complex separation methods usually are necessary to effect satisfactory resolution of the product mixtures. An improved process (a preferred process herein) for the preparation of trans-unsymmetrical bisanil adducts of diaminomaleonitrile (the preferred adducts herein) is illustrated by the following general scheme:

This four-step synthesis involves an initial condensation of 1 mole of diaminomaleonitrile with a first aryl aldehyde to give the monoanil adduct. In practice, any organic solvent can be used in this initial step, ketones and aldehydes which can react with diaminomaleonitrile being an exception. It is not necessary to have the diaminomaleonitrile in solution. Solvents which can be used in this condensation include tetrahydrofuran, ethyl Cellosolve, dimethylforrnamide, methanol, ethanol and mixtures thereof. A useful temperature range is 80C.; however, a temperature of 30C. is preferred and provides the best yield and quality of product. Reaction times of about 4-17 hours can be employed. Acid catalysts, such as sulfuric acid, hydrochloric acid, p-toluenesulfonic acid and trifluoroacetic acid, can be used. The monoanil can either be isolated or the reaction mixture containing same can be used in the next step.

Reduction of the monoanil, for example, with sodium borohydride, gives the N-benzyldiaminomaleonitrile derivative in high yield. Reduction of the monoanil adduct is a critical feature of the improved process in that it precludes the formation of undesirable mixtures during the subsequent condensation with Ar CI-IO (as was the case with the above-described two-step process). Preferably, an organic solvent is present during the reduction step; included among the preferred solvents are tetrahydrofuran, methanol, ethanol and ethyl Cellosolve, the latter being especially preferredv The addition of sodium borohydride provides an exothermic reaction and external cooling is necessary to keep the reaction temperature within the preferred l0-35C. range. Above C. the product obtained is of poor quality. The sodium borohydride normally can be added over a 20-40 minute period while still maintaining the temperature below 35C. Other reducing agents, such as lithium aluminum hydride and lithium borohydride, can also be used. The amount of reducing agent should be at least 0.50 mole per mole of monoanil to obtain complete reduction. The reduced monoadduct can be used without further purification in the next step of the reaction sequence. The reduction works best when at least some alcoholic solvent is present in the reaction mixture. Thus, the initial condensation of diaminomaleonitrile with Ar CHO in tetrahydrofuran (Tl-IF) to give the monoanil, as previously described, followed by addition of methanol to the TI-IF reaction mass and reduction of the monoanil with sodium borohydride, provides high yields of reduced monoadduct. In addition, by carrying out the initial condensation reaction at 2530C. rather than at or above the boiling point of tetrahydrofuran (65-66C.), for example, at C., and by keeping the subsequent reduction temperature below 25C., excellent yields, for example, greater than of theory, of the reduced monoadduct can be obtained.

Condensation of 1 mole of the reduced monoadduct with 1 mole of a second aryl aldehyde Ar CI-IO provides the monoreduced bisadduct. This step can be carried out with the same solvents and acidic catalysts used in the initial monocondensation step. However, best results are obtained when a solvent such as methanol or ethanol is used. In such a solvent the monoreduced bisadduct is very insoluble and precipitates as formed. Room (ambient) temperature (2530C.) is preferred in this step for maximizing purity of product; higher temperatures cause the product to darken considerably.

In order to obtain bisanil dyes having a red shade it is necessary, in many cases, to have a dialkylamino group on at least one of the aromatic rings. It is preferred to add the appropriate dialkylaminobenzaldehyde as the second aryl aldehyde rather than as the first aryl aldehyde since the monoanil formed from such an aldehyde is, in some cases, not reduced cleanly by sodium borohydride.

Oxidation of the monoreduced bisadduct in the final step of the four-step process with an oxidizing agent in an organic solvent provides the desired unsymmetrical bisanil dye accompanied, in some cases, by the colorless isomeric 2,3-dicyanoimidazole as shown in the aforesaid equations. The oxidation proceeds readily in tetrahydrofuran, acetonitrile, benzene, ethyl Cellosolve and acetone. However, in these solvents a large amount of imidazole is usually formed. Preferred solvents which give the bisanil dye and little or none of the isomeric imidazole are dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide and N-methylpyrrolidone. Oxidation at room (ambient) temperature (2530C.) is preferred over elevated temperatures. Oxidizing agents that can be used include the nickel oxides, MnO PbO 1 N dichlorodicyanoquinone and chloranil. Manganese dioxide gives the best yield and purity of dye and is preferred. In particular, carrying out the reaction with manganese dioxide in dimethylformamide at 30C. for about four hours provides an 80% yield of bisanil dye and the dye is completely free of the isomeric imidazole. The bisanil dyestuff can be conveniently isolated by adding tetrahydrofuran to the reaction mixture and filtering to remove insoluble manganese oxides, after which isopropanol is added to the filtrate and the precipitated solids are filtered off and washed with isopropanol; the precipitate is the desired bisanil dye.

Alternatively, in order to eliminate tetrahydrofuran from the above procedure, the reaction mass (after oxidation) is poured into water and, after acidification, hydrogen peroxide or sulfur dioxide is added thereto to dissolve the manganese oxides. The resultant mixture is then filtered and the crude dye thus obtained is washed thoroughly with isopropanol. The latter modification eliminates both the expensive tetrahydrofuran solvent and the tedious removal of the insoluble manganese salts, thus providing for a more economical process.

The geometry about the central carbon-carbon double bond of the bisanil prepared by the four-step pro cess is exclusively trans as evidenced by measurement 14 of the dipole moment. Thus, the preferred four-step process affords a high yield, for example. -80% overall from diaminomaleonitrile, of unsymmetrical transbisanil dyes uncontaminated with the cis isomer or the isomeric imidazole.

The symmetrical bisanil dyes previously discussed can also be prepared by the aforesaid four-step process but they are more advantageously prepared in good yield by the one-step process previously described.

As still another example of a process which can be employed herein is a two-step process by which can be prepared symmetrical or unsymmetrical bisanil dyes, and particularly such dyes which have a predominantly trans configuration. This process comprises heating diaminomaleonitrile in dimethylformamide under acidic conditions, preferably provided by sulfuric acid, with a molar equivalent of a first aryl aldehyde Ar CHO to produce a monoanil and then, employing the monoanil thus produced in place of diaminomaleonitrile, repeating the procedure with a molar equivalent of either the first aryl aldehyde Ar CHO or a second aryl aldehyde Ar CHO that is different from the first aryl aldehyde to produce either the symmetrical or unsymmetrical bisanil dye. The reaction times are very short, usually 10-30 minutes, and water produced during the condensations need not be removed to facilitate formation of the desired product. Although dimethylformamide is the preferred aprotic solvent, other solvents are useful, for example, dimethylacetamide, hexamethylphosphoramide, dimethylsulfoxide and N-methylpyrrolidone. The condensations are carried out in a temperature range of C. to the boiling point of the solvent. The preferred range is 140-l50C. Acidic catalysts, other than sulfuric acid, which are useful in providing acidic conditions include hydrochloric acid, ptoluenesulfonic acid and trifiuoroacetic acid.

Preferred symmetrical bisanil dyes herein include:

-continued The crude wet dye from any of the above processes is conveniently converted into a commercially usable form by mixing the crude dye, for example, ten parts on a 100% basis, with about 2.5 parts of a lignin sulfonate dispersant and water in a colloid or sand mill. Milling is continued until a fine, stable aqueous dispersion or paste is obtained, that is, until dye particle size is reduced to approximately one micron (average size).

Both the symmetrical and unsymmetrical bisanil dyes possess high tinctorial strengths and provide, on polyester, extremely bright, fluorescent yellow to blue dyeings having generally good fastness to sublimation and moderate fastness to light. These dyes are especially useful for dyeing and printing polyester where bright shades are desired. Because of the chemical versatility inherent in the preparative methods disclosed herein and because of the very high tinctorial strengths and breadth of shades obtainable, the bisanil dyes can be used in such a way as to suppress very undesirable coloration features without paying a color value penalty.

The bisanil dye can be applied to polyester fibers, either alone or in cellulosic blends, by an aqueous procedure, preferably under pressure, or by padding the fibers with an aqueous dispersion of the dye followed by dry heat (for example, Thermosol) fixation. Such dyeing procedures are widely used in the trade. The bisanil dyes are also useful for dyeing and printing polyester fibers, and their cellulosic blends, preferably employing a fabric which subsequently receives a durable press treatment.

The following experiments typify the aforementioned aqueous and Thermosol dyeing procedures.

Experiment 1 Aqueous (Pressure) Dyeing Procedure Five grams of commercially available polyester fabric were placed in an autoclave containing:

N=CH Br;

an aqueous dye paste 15% active ingredient) O.l gram containing the dye of Example 4 an anionic long chain sodium hydrocarbon 1.0 ml.

sulfonate solution) a nonionic long chain alcohol-ethylene oxide 0.5 ml.

adduct 10% solution) ethylenediaminetetraacetic acid, sodium salt 1.25 ml.

( l71 solution) butyl benzoate carrier l07c solution) 1.5 ml.

water to 75 ml.

acetic acid to adjust the pH The contents of the autoclave were heated for 1 hour at 265C. The dyed fabric was then rinsed in water and dried. The polyester fabric was dyed an extremely bright, fluorescent red shade.

Experiment 2 Thermosol Procedure A pad bath was prepared containing: an aqueous dye paste active ingredient) containing the dye of Example 5 grams purified natural gum thickener 20 grams water to 1 liter.

The pad bath was padded on commercially available /35 polyester/ cotton fabric with a pickup of 50-65 based on dry fabric weight (owf), followed by drying (infrared pre-drying followed by hot air or hot can drying is preferable) to remove the water. Thermosoling, by which the polyester component was dyed with the disperse dye, was accomplished by heating the dried pigment-padded fabric for seconds at 213C. Unfixed surface dye, on either the polyester or the cotton or both, was removed by padding the fabric from an aqueous bath containing 50 g./l. of sodium hydroxide and 40 g./l. of sodium hydrosulfite at 2739C., followed by steaming for 30 seconds. The fabric was then rinsed in water at 27C., scoured for minutes at 93C. in water containing 1% ether alcohol sulfate detergent, rinsed in water at 27C. and then dried. After dyeing and cleaning, the material was then padded (for permanent press treatment) with a pickup of 50-65% (owf) with a bath containing:

a dimethyloldihydroxyethyleneurea cross-linking agent 2000 a p-octylphenoxy(C H O), ,H wetting agent 2.5 a dispersed acrylic thermoplastic binding agent 22.5 a nonionic, paraffin-free. polyethylene emulsion which 22.5 serves as a fabric softener a nonionic polymer emulsion which imparts luster, a silky 30.0 hand and antistatic properties to the fiber a 20% aqueous zinc nitrate curing catalyst 36.0.

The resin-impregnated material was air dried to remove the water and then cured at 163C. for minutes. The durable-press treated polyester/cotton fabric was dyed an attractive, bright, fluorescent scarlet shade.

The following examples are given to illustrate the preparation of the bisanil dyes described above. All parts are given by weight unless otherwise noted.

EXAMPLE 1 PREPARATION OF SYMMETRICAL BISANlL A mixture of 2.16 parts of diaminomaleonitrile, 9.16 parts of 4-[N,N-bis(cyanoethyl)amino]benzaldehyde, 0.2 part of p-toluenesulfonic acid, 30 parts of dimethylacetamide (DMAC) and 150 parts of benzene was heated at 8090C. While benzene plus water was removed by distillation. After distillation for 17 hours, the remaining benzene was removed by distillation under nitrogen. After cooling the DMAC solution to 5C. 4.2 parts of red bisanil were collected by filtration; its m.p. was 2 l 8220C. Thin layer chromatography on silica gel-coated glass plates using benzeneacetonitrile (4: 1) as eluent showed one scarlet spot at an R, of 0.1. Calcd. for C H N C, 68.6; H, 5.0; N, 26.5%. Found: C, 68.2; H, 5.4; N, 26.5%. An infrared spectrum of a Nujol mull of the product showed no N-H absorption at 2.8-3.1 t. Based on the above, the product was of the structure p(NCl-l C NC H CH=NC(CN)=C(CN)N=CHC H4 PN(C2H4CN)2.

The mother liquor from the aforesaid filtration was poured into a large volume of ice-cooled water and the precipitated solids were isolated by filtration, washed with water and dried to give 3.9 parts of a red solid, mp. 185186C. Thin layer chromatography showed the presence of a minor scarlet spot at an R, of 0.1 and a major yellow spot at an R; of 0.6. The product showed absorption bands 515 my. (a,,,,,, of 10 liters gfcmf) for the bisanil and at 410 mp. (a of 87 li- A mixture of 3.24 parts of diaminomaleonitrile, 10.6 parts of 4-[N,N-bis( ethyl)amino]benzaldehyde and 50 parts of glacial acetic acid was stirred at ll5120C. for 4 hours. After standing at 2530C. for 18 hours. the solids were collected. washed with 25 parts of cold acetic acid, then with two 25-part portions of isopropanol and dried to give 5.3 parts (60.8% yield) of the symmetrical bisanil dye as dark blue metallic flakes, m.p. 268270C. The dye had an absorptivity (a,,,,,, of 265 liters g."cm. at a wavelength (X of 561 mu. Based on the above. the dye was of the structure p( H O; NC H CH=NC(CN )=C(CN)N= Cl-lC ll pN(C l-l A similar result was obtained by starting with the appropriate monoanil derivative instead of diaminomaleonitrile.

EXAMPLE 3 PREPARATION OF UNSYMMETRICAL BISANIL BY A TWO-STEP PROCESS a. A mixture of 132 parts of diaminomaleonitrile, 2 10 parts of 4-[N,N-bis(ethyl)amino]benzaldehyde, 30 drops of concentrated sulfuric acid and 2,000 parts of tetrahydrofuran (THF) was heated at 65C. for 3 hours. The tetrahydrofuran was partially evaporated and 1,000 parts of ethanol were added. The precipitated solids were isolated by filtration and air dried to give 227 parts of yellow monoanil (76% yield). A mixture of 14.1 parts of 4-chlorobenzaldehyde, 20 drops of piperidine and 500 parts of benzene was heated at 8090C. while continuously azeotroping the water formed during the reaction. The monanil (13.4 parts) was then added in portions over a 6-hour period and heating at 8090C. was continued for an additional 2 hours. The solvent was removed by distillation and the resultant solid residue was boiled with 200 parts of isopropanol. After filtration and drying, 9.2 parts (47% yield) of red product were obtained, m.p. 207208C. Thin layer chromatography showed the major component to be the unsymmetrical dye along with small amounts of purple impurities. The dye had an absorptivity (a,,, of 177 liters gfcmf at a wavelength (h of 528 m,u. Calcd. for C l-l N Cl: C, 67.8; H, 5.2; N, 18.0%. Found: C, 68.6; H, 5.6; N, 17.9%. Based on the above, the dye was of the structure pClC H.,Cl-l=N-C(CN)=C(CN)N=CHC 4P 2 s)2- b. A mixture of 6.7 parts of the monoanil of part (a), 7.05 parts of 4-chlorobenzaldehyde, 0.85 part of piperidine and 250 parts of benzene was heated at 8090C. for 1 hour while continuously azeotroping the water formed during the reaction. Thin layer chromatography of the reaction mixture showed the presence of approximately equal amounts of the trans-symmetrical and -unsymmetrical bisanil dyes; only traces of cisbisanil dyes could be detected.

c. When the condensation was run on the same scale but in the presence of only 1 drop of piperidine, the major products after 1 hour at 8090C. were the cissymmetrical and -unsymmetrical bisanil dyes. Only traces of trans-bisanil dyes were present.

EXAMPLE 4 PREPARATION OF UNSYMMETRICAL BISANIL BY A FOUR-STEP PROCESS A mixture of 21.6 parts of diaminomaleonitrile, 38.3 parts of 4-bromobenzaldehyde, 5 drops of concentrated sulfuric acid and 250 parts of tetrahydrofuran was stirred at 2530C. for 4 hours. Methanol parts) was added and 7.95 parts of sodium borohydride were added in portions over a 20-minute period while maintaining the temperature at 2025C. by external cooling in ice water. After stirring for minutes at 25C. most of the solvent was removed by distillation. The remaining solution was poured into 1.500 parts of ice-cooled water and stirred for 1 hour; the resultant solids were collected and air dried to give 53.5 parts (97% yield) of the reduced monoadduct. This material was used in the next step of the reaction se quence without purification.

A slurry of 53 parts of the reduced monoadduct, 38.8 parts of 4-[N,N-bis(cthyl)amino]benzaldehyde, 1.2 parts of concentrated sulfuric acid and 1,000 parts of ethanol was stirred for 4 hours at 30C. The reaction mixture was filtered and the collected solids were air dried, yielding 83 parts (99% yield) of orange reduced bisadduct. This product was of sufficient purity to use in the next reaction without purification.

A mixture of 82 parts of the reduced bisadduct, 75 parts of manganese dioxide and 500 parts of dimethylformamide was stirred for 4 hours at 25-30C. Tetrahydrofuran (500 parts) was added and the resulting mixture was filtered through a medium porosity, sintered glass funnel. The solids thus obtained were washed with four 400-part portions of tetrahydrofuran to dissolve and separate the precipitated bisanil dye from the insoluble manganese oxides. The combined tetrahydrofuran filtrates were concentrated under reduced presure to a thick slush; 600 parts of isopropanol were added and the resultant slurry was filtered: the collected solids were washed with three 100-part portions of isopropanol to give 61.5 parts (75.6% yield) of bisanil dye, as metallic green flakes, exhibiting an absorptivity (a,,,,,, of 153 liters gfcmf at a wavelength (A of 531 mu. Recrystallization of the product from benzene gave very dark needles, mp. 205206C.; it exhibited an a of 166 liters gfcm. at a X of 531 mu. Calcd. for C H N Br: C, 60.8; H, 4.7; N, 16.1%. Found: C, 59.5; H, 4.8; N, 15.6%. Thin layer chromatographic analysis of the product showed only a single purple spot. Based on the above, the dye was of the structure p-Br-C H CI-I- =NC(CN)=C(CN)N=CHC H pN(C H5)2.

EXAMPLE 5 PREPARATION OF UNSYMMETRICAL BISANIL BY A FOUR-STEP PROCESS A mixture of 10.8 parts of diaminomaleonitrile, 15.6 parts of l-naphthaldehyde, 5 drops of concentrated sulfuric acid and 125 parts of tetrahydrofuran was stirred at 2530C. for 17 hours. Methanol (35 parts) was added and the solution was cooled to 15C. Sodium borohydride (3.8 parts) was added in portions while maintaining the temperature between 1520C. by external water-ice cooling. After stirring for 15 minutes. the solution was poured into 1,500 parts of ice-cooled water and stirred for 3 hours; the solids (the reduced monoadduct as a light tan powder) were removed by filtration.

A slurry of the reduced monoadduct, 18 parts of 4- [N,N-bis(ethyl)amino]benzaldehyde, 15 drops of concentrated sulfuric acid and 200 parts of ethanol was stirred for 17 hours at 25-30C. The solids were isolated by filtration, yielding 35.4 parts of the reduced bisadduct as an orange powder.

A mixture of the reduced bisadduct, 35 parts of manganese dioxide and 150 parts of dimethylformamide was stirred for 5 hours at 2530C. The solids were isolated by filtration and washed with four 400-part portions of tetrahydrofuran to give a solution of the desired bisanil dye. The tetrahydrofuran and dimethylformamide were distilled off under reduced pressure and the solids thus obtained were washed with isopropanol and dried, yielding 32.5 parts yield) of bisanil dye as a dark red powder. mp. 21 1-213C.; it exhibited an absorptivity (a,,,,,, )of 183 liters gfcmf at a wavelength (A of 540 mu. Calc'd. for C ,,H N C. 77.0; H. 5.7; N, 17.3%. Found: C, 76.3: H, 5.6; N, 17.4%. Thin layer chromatography showed only a single purple spot. Based on the above, the dye was of the structure EXAMPLE 6 PREPARATION OF UNSYMMETRICAL BISANIL BY A FOUR-STEP PROCESS Example 5 was substantially repeated except that another solvent was used in place of tetrahydrofuran in both the reduction and oxidation steps. To a slurry of 12.7 parts of the monoanil of Example 5 in 50 parts of ethyl Cellosolve was added in portions, 0.95 part of sodium borohydride while maintaining the temperature of 2535C. by external cooling in ice-cooled water. The resulting solution was stirred for 30 minutes, poured into 500 parts of ice water and stirred for 1 additional hour. The light tan precipitate was collected by filtration and air dried to give 12.4 parts yield) of reduced monoadduct.

The reduced monoadduct was condensed with 4- [N,N-bis( ethyl)amino]benzaldehyde in ethanol as described in Example 5 to yield the reduced bisadduct.

A mixture of 5.0 parts of the reduced bisadduct, 5.0 parts of manganese dioxide and 35 parts of dimethylformamide was stirred for 2 hours at 2530C. The solution was poured into 350 parts of ice-cooled water and 9 parts of concentrated sulfuric acid were added. Hydrogen peroxide (6 parts of a 30% aqueous solution) was added in portions to dissolve the manganese oxides. The resulting mixture was filtered and the crude dye thus obtained was washed with two 50-part portions of isopropanol and dried to give 4.5 parts (89.4% yield) of the bisanil dye, as a red solid, exhibiting an absorptivity (a of 169 liters g."cm. at a wavelength (A of 540 my Thin layer chromatography showed only a single purple spot; the R, was identical to that of the dye of Example 5.

EXAMPLE 7 PREPARATION OF UNSYMMETRICAL BISANIL BY A FOUR-STEP PROCESS The dye of Example 4 was also prepared by reaction of the reduced bisadduct (9.6 parts) with 10.6 parts of lead dioxide (0.04 mole) in 200 parts of acetonitrile at 5055C. for 9 hours. The suspended lead sludge was filtered off and the solvent was evaporated. Thin layer chromatography showed the residue to consist of approximately equal amounts of the unsymmetrical bisanil dye of Example 4 and the colorless isomeric imidazole. The imidazole was removed by prolonged extraction of the solid with hot (8090C.) ethanol; the extracted product was shown by thin layer chromatography to consist of a single purple spot. The analytical data obtained on the product was substantially the same as that reported in Example 4.

EXAMPLE 8 PREPARATION OF SYMMETRICAL BISANIL A mixtureof 9.4 parts of 4-[N,N-bis(ethyl)amino]- benzaldehyde, 2.16 parts of diaminomaleonitrile, 4.0 parts of phosphorus pentoxide, 6 drops of concentrated sulfuric acid and 70 parts of hexamethylphosphoramide was stirred at 50-5 C. for 6 hours. After each 2-hour period, an additional 1.0 part of phosphorus pentoxide was added. The reaction mixture was then poured into 800 parts of water containing 20 parts of aqueous ammonium hydroxide. After stirring for 1 hour, the precipitated solids were collected by filtration, washed with water and dried to yield 5.5 parts (65% yield) of symmetrical bluish-red bisanil, m.p. 140-142C. The product was recrystallized three times from isopropanol, providing an analytically pure sample, m.p. 162165C. The product exhibited a high intensity absorption band (105 liters g. cm. at a wavelength of 558 my. and, in addition, two lower intensity bands at 400 mg. (61.5 liters g. cm.) and 382 my. (56 liters gfcmf). Based on the presence of the lower wavelength absorption bands and the large observed dipole moment of 14.6 Debye, the product was confirmed as having cis geometry about the central carbon-carbon double bond. Based on the above, the structure is p(I-I C N-C I-I -CH- =N-C(CN)=C(CN)N=CI-IC H p-N(C l-I EXAMPLE 9 PREPARATION OF SYMMETRICAL BISANIL A mixture of 10.8 parts of diaminomaleonitrile, 29.0 parts of indole-3-carboxaldehyde, 400 parts of tetrahydrofuran and 10 drops of concentrated sulfuric acid was stirred at 65C. for 16 hours. The tetrahydrofuran was partially evaporated and 10 parts of 10% aqueous sodium carbonate were added. The precipitated solids were isolated by filtration, washed with water, then with isopropanol and dried to give 20.3 parts of yellow monoanil (86% yield), m.p. 227.5229C.

A mixture of 14.1 parts of the monoanil, 12.0 parts of concentrated sulfuric acid, 11.6 parts of indole-3-carboxaldehyde and 150 parts of dimethylformamide was heated in about 10 minutes to l45150C.; it was maintained at this temperature for 20 minutes. The reaction mixture was then'poured into 1,000 parts of water. The precipitated solids were collected by filtration,

washed with water, then with isopropanol and dried.

The product was recrystallized three times from acetonitrile-chloroform to give 6.85 parts (31.7% yield) of the symmetrical yellow bisanil, m.p. 331333C. The dye had an absorptivity (a,,,,,,,.) of 220 liters gfcm. at a wavelength (A of 480 mu. Calcd. for C H N C, 72.9; H, 3.9; N, 23.2%. Found: C, 71.4; H, 4.3; N, 22.3%. Based on the above, the structure of the dye is EXAMPLE l0 PREPARATION OF UNSYMMETRICAL BISANIL A mixture of 4.7 parts of indole-3-carboxaldehydediaminomaleonitrile monoanil, 3.54 parts of 4-[N,N- bis(ethyl)amino]benzaldehyde, 4.0 parts of concentrated sulfuric acid and 50 parts of dimethylformamide was heated at l150C. for 20 minutes. The reaction mixture was then poured into 1,000 parts of water. The precipitated solids were filtered off, washed with water and dried. Thin layer chromatographic analysis showed the presence of the two possible symmetrical bisanil condensates, together with a third bright reddish-orange component. The latter material was isolated from the product mixture by column chromatography on Florisil using chloroform as eluent. After two recrystallizations from acetonitrile, a small amount (0.10 part) of the pure unsymmetrical bisanil conden- .sate was obtained, m.p. 265268C. Infrared analysis showed an NH band at 3395 cm. and CN absorption at 2200 cm. and 660 cm. The visible absorption spectrum exhibited alt of 522 mu and an a of 239 liters g.' cm.'. Based on the above, the structure of the dye is EXAMPLE l1 PREPARATION OF SYMMETRICAL BISANIL A mixture of 2.16 parts of diaminomaleonitrile, 3.5 parts of 4-[N,N-bis(ethyl)amino1benzaldehyde, 8.0 parts of concentrated sulfuric acid and parts of dimethylformamide was stirred at l45150C. for 20 minutes. The reaction mixture was then poured into 1,000 parts of water", the precipitated solids were colpearing as column headings in the table correspond to the substituents shown in the formula lected by filtration, washed with water and dried. The product was purified by column chromatography on Florisil using chloroform as eluent, yielding 0.47 part of bluish-red bisanil, m.p. 265268C. It exhibited an absorptivity (a,,,,,,, of 265 liters gfcm at a wavelength of 561 mu. A nuclear magnetic resonance (NMR) spectrum of the product was found to be identical to that of the dye of Example 8. However, the absence of any lower wavelength absorption, together with the much higher melting point and a low observed dipole moment of 3.2 Debye indicates that the product is actually the trans form of the dye of Example 8.

The isomerization of the cis dye of Example 8 to the trans form of this example was readily effected by heating the former dye in benzene containing a small amount of iodine. The resultant product was identical in m.p. and spectral properties to the trans isomer.

EXAMPLES 12-1 18 Symmetrical bisanil dyes were prepared (Examples' 12-19) by procedures similar to that described in Ex- The groups shown in column Y for Examples 34, 39,

15 82, 87, 88 and 95 correspond to the entire group 27, 31, 49, 50, 52, 53, 55, 61, 62, 64, 65, 66, 70, 76, 7883, 89-99 and 118 correspond to the entire group ample 2. Unsymmetrical bisanil dyes were prepared A (Examples 20-118) by preferred four-step processes similar to those described in Examples 4 and 5. Data for the dyes produced are shown in Table II. Except as B noted below the substituents A, B, C, X, Y and Z ap- C TABLE II Example NO. A B c x Y Z 12 H H H H H H 13 H (4)N(n H H (4)N(n-C H1)z H 3 14 H 4' 0CH H H 4 0CH H 15 2' 0CH 4' -OCH H 2) OCH 4 -0CH H l6 H (4')N(C2Hs) H H (4)N(C2H5)C2H4CN H C H,CN 17 (2') CH3 (4')N(C2H5) H :l (4)N(C2H5)C2H-1CN H C2H4CN l8 (2)C1 (4')N(CH:1)2 H (2) 3)2 H 19 H (4')N(CH:) H H (4)N(CH;,)C2H4CO2 H c 11,c0. c11, CH 20 H H H H 4 N(CH3)C2H4CN H 21 H (4')-C1 H H (4)N(CH )C H.CN H

Elemental Analysis Example M a Shade on Calculated Found No. (mp) (l.g."cm.") Polyester C H N C H N 12 432 Yellow 58.4 7.4 34.2 57.9 6.8 34.5 13 561 205 Bluish 74.5 7.9 17.6 73.6 7 2 177 Red 14 427 159 Greenish 69.8 4.7 16.3 69.3 4.8 15.1

Yellow 15 460 170 Yellow 16 540 215 Red 70.6 5.9 23.5 70.2 6.0 22.6 17 550 171 Bluish 71.4 6.4 22.5 71.7 6.7 1.9

Red 18 555 223 Bluish 60.2 4.6 19.1 60.3 4.7 19.5 19 543 194 Red 654 5.9 16.3 64.2 5.4 16.0 20 500 141 Bright 72.1 4.9 22.9 72.0 4.9 22.9

Orange 21 510 168 Orange 65.9 4.2 21.0 64.7 4.1 21.2

3. Dye of claim 1 wherein Ar and Ar are different.

4. Dye of claim 1 wherein the cyano groups are in the cis configuration about the carbon-carbon double bond.

5. Dye of claim 1 wherein the cyano groups are in the trans configuration about the carbon-carbon double bond. t

6. Dye of claim 2 wherein each of Ar, and Ar is e 4 P 2 4 )2'- 7. Dye of claim 2 wherein each of Ar and Ar is p- N,N-diethylaminophenyl.

8. Dye of claim 2 wherein each of Ar and Ar is C l-l N 9. Dye of claim 2 wherein each of Ar and Ar is ochloro-p-N,N-dimethylaminophenyl.

l0. Dye of claim 2 wherein each of Ar and Ar is cn. N

\ canco cn.

11. Dye of claim 3 wherein Ar is p-chlorophenyl and Ar is p-N,N-diethylaminophenyl.

12. Dye of claim 3 wherein Ar is p-bromophenyl and Ar is p-N,N-diethylaminophenyl.

13. Dye of claim 3 wherein Ar is l-naphthyl and Ar is p-N,N-diethylaminophenyl.

l4. Dye of claim 3 wherein Ar is o,o-dichlorophenyl and Ar is p-N,N-diethylaminophenyl.

l5. Dye of claim 3 wherein Ar is l-naphthyl and Ar is 16. Dye of claim 3 wherein Ar is o,o-dichlorophenyl and Ar is o-methyl-p-N,N-diethylaminophenyl.

l7. Dye of claim 3 wherein Ar is l-naphthyl and Ar is o-methyl-p-N,N-diethylaminophenyl.

l8. Dye of claim 3 wherein Ar is 2-hydroxyl -naphthyl and Ar is p-N,N-diethyla.minophenyl.

19. Dye of claim 3 wherein Ar is 2-hydroxy-l-naphthyl and Ar is o-methyl-p-N,N-diethylaminophenyl.

20. Dye of claim 3 wherein Ar is l-naphthyl and Ar is o-methyl-p-N,N-di-n-butylaminophenyl.

21. Dye of claim 3 wherein Ar is m-nitrophenyl and Ar is p-N,N-diethylaminophenyl.

22. Dye of claim 3 wherein Ar is p-N,N-diethylaminophenyl and Ar is 4-thiomethoxyphenyl.

23. Process of preparing the bisanil dye of claim 1, which process comprises the steps:

l. condensing diaminomaleonitrile and the aromatic aldehyde Ar Cl-lO to produce the monoanil Ar- CH=HC(CN)=C(CN)-NH 2. reducing the monoanil from step (1) to produce Ar Cl-I NHC(CN)=C(CN)NH 3. condensing the product from step (2) and the aromatic aldehyde Ar CHO, which aldehyde is the same as or different from the aldehyde of step (1), to produce the monoanil Ar CH N- H-C(CN)=C(CN)N=CHAr and 4. oxidizing the monoanil from step (3) to produce the bisanil Ar CH=NC(CN)=C(CN)-N=). CHAr Ar and Ar being as defined in claim 1.

same.

25. Process of claim 23 wherein Ar and Ar are different.

26. Process of claim 25 wherein Ar is p-N,N-diethylaminophenyl and Ar is 4-thiomethyoxyphenyl.

27. Process of claim 23 wherein the oxidizing agent employed in step (4) is lead dioxide.

28. Process of claim 23 wherein the reducing agent employed in step (2) is sodium borohydride.

29. Process of claim 23 wherein step (1) is carried out in the presence of an organic solvent other than a ketone or aldehyde which can react with diaminomaleonitrile, at a temperature of 2080C., for 4-17 hours; step (2) is carried out in the presence of an organic solvent, at a temperature not in excess of 35C., with at least 0.50 mole of reducing agent per mole of monoanil; and steps (3) and (4) are carried out in the presence of an organic solvent, at ambient te mperature.

30. Process of claim 29 wherein an acid catalyst is employed in steps (1) and (3) and the temperature. in step (2) is lO-35C.

31. Process of claim 30 wherein in steps (1) and (3) the solvent is selected from tetrahydrofuran, ethyl Cellosolve, dimethylformamide, methanol, ethanol and mixtures thereof, the acid catalyst is selected from sulfuric acid, hydrochloric acid, p-toluenesulfonic acid and trifluoroacetic acid and the temperature is 2530C.; in step (2) the solvent is selected from tetrahydrofuran, methanol, ethanol and ethyl Cellosolve and the temperature is less than 25C; and in step (4) the solvent is selected from tetrahydrofuran, acetonitrile, benzene, ethyl Cellosolve, acetone, dimethylformarnide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, and N-methylpyrrolidone and the temperature is 2530C.

32. Process of claim 31 wherein the solvent employed in step (2) is methanol or ethanol.

33. Process of preparing the bisanil dye of claim 1, which process comprises the steps:

1. condensing diaminomaleonitrile and a molar equivalent of the aromatic aldehyde Ar CHO, in the presence of an organic solvent selected from the group consisting of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, dimethylsulfoxide and N-methylpyrrolidone, under acidic conditions, at a temperature in the range C. to the boiling point of the solvent, to produce the monoanil Ar CH=N-C(CN)#I(C- N)NH and 2. condensing the monoanil from step (1) and a molar equivalent of the aromatic aldehyde Ar CHO, which aldehyde is the same as or different from the aldehyde of step (1), in the presence of an 24. Process of claim 23 wherein Ar and Ar are the 

1. BISANIL DYE OF THE FORMULA
 2. condensing the monoanil from step (1) and a molar equivalent of the aromatic aldehyde Ar2CHO, which aldehyde is the same as or different from the aldehyde of step (1), in the presence of an organic solvent selected from the group consisting of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, dimethylsulfoxide, and N-methylpyrrolidone, under acidic conditions, at a temperature in the range 140*C. to the boiling point of the solvent, to produce the bisanil Ar1-CH N-C(CN) C(CN)-N CH-Ar2, Ar1 and Ar2 being as defined in claim
 1. 2. reducing the monoanil from step (1) to produce Ar1CH2NH-C(CN) C(CN)-NH2;
 2. Dye of claim 1 wherein Ar1 and Ar2 are the same.
 3. Dye of claim 1 wherein Ar1 and Ar2 are different.
 3. condensing the product from step (2) and the aromatic aldehyde Ar2CHO, which aldehyde is the same as or different from the aldehyde of step (1), to produce the monoanil Ar1CH2NH-C(CN) C(CN)-N CH-Ar2; and
 4. oxidizing the monoanil from step (3) to produce the bisanil Ar1-CH N-C(CN) C(CN)-N CH-Ar2, Ar1 and Ar2 being as defined in claim
 1. 4. Dye of claim 1 wherein the cyano groups are in the cis configuration about the carbon-carbon double bond.
 5. Dye of claim 1 wherein the cyano groups are in the trans configuration aBout the carbon-carbon double bond.
 6. Dye of claim 2 wherein each of Ar1 and Ar2 is C6H4-p-N(C2H4CN)2.
 7. Dye of claim 2 wherein each of Ar1 and Ar2 is p-N,N-diethylaminophenyl.
 8. Dye of claim 2 wherein each of Ar1 and Ar2 is
 9. Dye of claim 2 wherein each of Ar1 and Ar2 is o-chloro-p-N,N-dimethylaminophenyl.
 10. Dye of claim 2 wherein each of Ar1 and Ar2 is
 11. Dye of claim 3 wherein Ar1 is p-chlorophenyl and Ar2 is p-N, N-diethylaminophenyl.
 12. Dye of claim 3 wherein Ar1 is p-bromophenyl and Ar2 is p-N, N-diethylaminophenyl.
 13. Dye of claim 3 wherein Ar1 is 1-naphthyl and Ar2 is p-N,N-diethylaminophenyl.
 14. Dye of claim 3 wherein Ar1 is o,o-dichlorophenyl and Ar2 is p-N,N-diethylaminophenyl.
 15. Dye of claim 3 wherein Ar1 is 1-naphthyl and Ar2 is
 16. Dye of claim 3 wherein Ar1 is o,o-dichlorophenyl and Ar2 is o-methyl-p-N,N-diethylaminophenyl.
 17. Dye of claim 3 wherein Ar1 is 1-naphthyl and Ar2 is o-methyl-p-N,N-diethylaminophenyl.
 18. Dye of claim 3 wherein Ar1 is 2-hydroxy-1-naphthyl and Ar2 is p-N,N-diethylaminophenyl.
 19. Dye of claim 3 wherein Ar1 is 2-hydroxy-1-naphthyl and Ar2 is o-methyl-p-N,N-diethylaminophenyl.
 20. Dye of claim 3 wherein Ar1 is 1-naphthyl and Ar2 is o-methyl-p-N,N-di-n-butylaminophenyl.
 21. Dye of claim 3 wherein Ar1 is m-nitrophenyl and Ar2 is p-N, N-diethylaminophenyl.
 22. Dye of claim 3 wherein Ar1 is p-N,N-diethylaminophenyl and Ar2 is 4-thiomethoxyphenyl.
 23. Process of preparing the bisanil dye of claim 1, which process comprises the steps:
 24. Process of claim 23 wherein Ar1 and Ar2 are the same.
 25. Process of claim 23 wherein Ar1 and Ar2 are different.
 26. Process of claim 25 wherein Ar1 is p-N,N-diethylaminophenyl and Ar2 is 4-thiomethyoxyphenyl.
 27. Process of claim 23 wherein the oxidizing agent employed in step (4) is lead dioxide.
 28. Process of claim 23 wherein the reducing agent employed in step (2) is sodium borohydride.
 29. Process of claim 23 wherein step (1) is carried out in the presence of an organic solvent other than a ketone or aldehyde which can react with diaminomaleonitrile, at a temperature of 20*-80*C., for 4-17 hours; step (2) is carried out in the presence of an organic solvent, at a temperature not in excess of 35*C., with at least 0.50 mole of reducing agent per mole of monoanil; and steps (3) and (4) are cArried out in the presence of an organic solvent, at ambient temperature.
 30. Process of claim 29 wherein an acid catalyst is employed in steps (1) and (3) and the temperature in step (2) is 10*-35*C.
 31. Process of claim 30 wherein in steps (1) and (3) the solvent is selected from tetrahydrofuran, ethyl Cellosolve, dimethylformamide, methanol, ethanol and mixtures thereof, the acid catalyst is selected from sulfuric acid, hydrochloric acid, p-toluenesulfonic acid and trifluoroacetic acid and the temperature is 25*-30*C.; in step (2) the solvent is selected from tetrahydrofuran, methanol, ethanol and ethyl Cellosolve and the temperature is less than 25*C; and in step (4) the solvent is selected from tetrahydrofuran, acetonitrile, benzene, ethyl Cellosolve, acetone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, and N-methylpyrrolidone and the temperature is 25*-30*C.
 32. Process of claim 31 wherein the solvent employed in step (2) is methanol or ethanol.
 33. Process of preparing the bisanil dye of claim 1, which process comprises the steps:
 34. Process of claim 33 wherein the acidic conditions are provided by sulfuric acid, hydrochloric acid, p-toluene-sulfonic acid or trifluoroacetic acid.
 35. Process of claim 34 wherein the acid is sulfuric acid, the temperature is 140*-150*C., the solvent is dimethylformamide and the reaction time is 10-30 minutes.
 36. Process of claim 33 wherein Ar1 is p-N,N-diethylaminophenyl and Ar2 is 4-thiomethoxyphenyl. 